Discharge lamp



A ril 5, 193 8. E. c. BRUECKMANN DISCHARGE LAMP Filed Jan. 10, 1955 Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE DISCHARGE LAMP Application January 10, 1935, Serial No. 1,142

9 Claims.

This invention relates to discharge devices and more particularly to devices in which a metallic vapor is employed as the ionizable medium.

In certain devices of the above character and particularly in devices using sodium, cadmium, mercury or other vapor condensable at room temperature, it is necessary to provide a relatively high voltage to start the device. Although it is the practice to include a rare gas such as argon or neon to promote starting in the above devices, a relatively high starting voltage is required, whereas when the metal sodium, for example, is vaporized, the device operates at relatively low voltage. It is necessary, however, in order to gain the benefit of low voltage for starting, to heat the vaporizable material. Furthermore, when lamps of the above character are operated under low temperature conditions, as when used out of doors in cold climates, great difliculty is encountered in starting. F

Lamps as heretofore constructed start at 150 volts at a temperature of 25 degrees centigrade, at 200 volts at a temperature of zero degrees centigrade and at 300 volts at a temperature of ten below zero centigrade. This makes them impractical for outdoor .winter service.

It is, therefore, an object of the present invention to provide a lamp of the character described which will start at relatively low voltage at relatively low temperature.

Another object of the invention is to provide a lamp in which a heat source is furnished to facilitate starting.

A further object of the invention is to provide a lamp wherein a source of heat is provided to facilitate starting and in which the heat supply is terminated when the lamp reaches an operating temperature,

Other objects and advantages of the invention will be more clearly understood by reference to the following description, together with the accompanying drawing, in which- Fig. 1 is a side elevational view of a device constructed in accordance with-the present invention;

Fig. 2 is a view taken on line II-II in Fig. 1; and.

Fig. 3 is a view taken on line IIIIII in Fig. 1.

A device constructed in accordance with the present invention may comprise a tubular sealed envelope Hl having electrodes II and I2 mounted on conductive support members lil and I4 respectively and sealed through opposite ends walls of the envelope. The electrodes may be of any suitable construction in which a metallic body is provided with an electron emission material. An electrode of this character is shown and described in copending application Serial No. 733,168 filed June 30, 1934 and assigned to the present assignee.

The bulb l may be mounted in an outer sealed envelope or jacket 15 having a press 16 at one end.- The jacket l provides an outer heat insulating chamber for the discharge envelope I 0. The conductor 14 of the electrode I 2 is sealed through the press It and connects with a lead wire or conductor 11. The conductor 13 of the electrode II is connected, as by means of a wire H, with a conductive supporting member I8 which member is sealed through the press 16 and connected to a conductor or leadwire l9. The supporting conductor I8 is provided with arms 2| which embrace and support the envelope 10.

A heater element or filament 22 is disposed at one end, preferably at the lower end, of the jacket or chamber 15. This filament may be of tungsten wire helically wound and in the form of a ring having one terminal 23 connected with the conductive support 18 and the other terminal 24 connected with a conductor 25. Support wires 26 extending from a button of glass, or other insulative material, may be employed to support the filament and the button may be mounted on an end of the lead wire l3 extending from the chamber H).

The conductor 25 may be supported by means of a connector piece 21 which is secured in the press IS. The conductor 25 may be insulated throughout substantially its length and provided with an exposed contact portion 28 for engagement with an end of a heat responsive element in the form of a. bimetallic member 29. The other end of the member 29 may be connected by means of a conductor 3| to the conductor l4 and consequently with the lead wire H. For the purpose of supporting conductor 25 in fixed relation to the bulb, a pair of resilient members 32 and 33 are provided.

Each of these members mayinclude a strip 34 in the form of a ring of less diameter than the inside diameter of the outer jacket and tension members 35 may be' provided to hold the rings in resilient spaced relation with respect to the surface of the outer jacket. Connector members l1 and 19, current flows through the filament 22, conductor I8 and lead wire l9. Owing to the in itial resistance within the bulb l0 before'ionization occurs, substantially all the current will flow through the filament heating it to relatively high temperature. A voltage drop, however, occurs between the electrodes and they become emissive, ionizing the gas and a discharge occurs so that current flows through conductor l4, through the ionized gas, conductor l3 and through conductor I8 to lead wire l9. As the device heats up the thermostat which is in close proximity to the wall of the chamber I0 is affected and the bimetallic member moves to break the circuit cutting out the filament, thus permitting the full current flow between the electrodes.

If for any reason the current is terminated and no discharge occurs, the device will cool down and the vapor will condense. At a predetermined temperature the bimetallic member will again cause current to flow through the filament when the current flow is reestablished. Thus the temperature of the device will be elevated with the result that the metallic vapor such as, for example, mercury vapor will again be vaporized for ionization and a discharge will occur between the electrodes. 7

When a lamp as above described is put into operation the heater element will radiate sufficient heat to vaporize the ionizable medium so that when suflicient voltage is impressed between the electrodes they will become heated and electron emissive causing a dischargecurrent to flow and the device to operate. The heat from the discharge then causes the heat responsive element to break the heater circuit. If the lamp becomes inoperative by reason of a temporary interruption of current, the heat-responsive element will still keep the heater circuit open as long as the lamp is hot enough to act upon the said element. element will not elevate the temperature of the device to such a degree as to prevent restarting.

Although it is desirable to provide a cut-out means for terminating the flow of current through the filament it maybe desirable to have the filament heated during the operation of the lamp especially when the lamp is operated out of doors in very cold weather. In such case the filament will receive part of the full current flow and emanate a given amount of heat energy.

A high intensity mercury lamp of the present character may be operated at 150 volts across the lamp on a line voltage of from 208 to 240 volts, a reactance being used-in series with the lamp. The lamp may, however, start at a considerably higher voltage than the voltage at which it operates. As the temperature drops below or rises above normal room temperature there is a considerable increase in the starting voltage. Thus, if the temperature of the lamp is low, re-- sulting in an increase in the starting voltage the heater element as provided in accordance with the present invention decreases the starting voltage from say 300 volts to 200 volts by raising the temperature of the lamp from zero degrees centigrade to 20 degrees centigrade.

Although a preferred embodiment of the invention is shown and described herein it is to be understood that modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed:

1. A discharge device comprising a sealed en- -Thus the heat from the heater velope, containing a metallic vapor, electrodes in said envelope, a heater element, a heater circuit including said heater element, a heat responsive element for making and breaking said circuit disposed intermediate the ends of said envelope, a discharge circuit including said electrodes when said vapor is ionized to carry a discharge current, said heat responsive element operating to break said heater circuit when said.

discharge elevates the temperature of said element to a predetermined degree, said element operating upon a decrease in temperature to close said circuit for a flow of current through said heater.

2. A discharge device comprising a sealed envelope, containing a metallic vapor, electrodes in said envelope, a heater element, a heater circuit including said heater element, a heat responsive element for making and breaking said circuit, a

discharge circuit including said electrodes when said vapor is ionized to carry a discharge current, said heat responsive element positioned between said electrodes and adjacentto the path of discharge and operating to break said heater circuit when said discharge elevates the temperature of said element to a predetermined degree.

3. A discharge device comprising sealed outer and inner envelopes, an ionizable medium in said inner envelope, a pair of electrodes in said inner envelope, a heater element in said outer envelope positioned to radiate heat energy to said inner envelope, means for causing a flow of electrical energy through said envelopes, means for producing a discharge between said electrodes, and an element within said outer envelope responsive to heat radiated from said discharge for making and breaking the circuit through said heater element, and disposed intermediate said electrodes, to terminate the flow of electrical energy in said heater element when the heat of the discharge raises said heat-responsive element to a predeterminedtemperature.

4. A discharge device comprising sealed outer and inner envelopes, an ionizable medium in said inner envelope, a pair of electrodes in said inner envelope, a heater element in said outer envelope positioned to radiate heat energy to said inner envelope, means for causing a flow of electrical energy through said envelopes, means for producing a discharge between said electrodes, and an element within said outer envelope disposed in close relation to the discharge path and intermediate the ends thereof, either responsive to heat radiated from said discharge to terminate the flow of electrical energy in said heater element, or operating to cause a flow of electrical energy through said heater element.

5. A discharge device comprising an inner and an outer chamber, an ionizable medium and electrodes disposed at opposite ends of said inner chamber, a heater element in said outer chamber, an electrical circuit for said heater, a bi-metallic element in said circuit and positioned Within said outer chamber and intermediate said electrodes to be heated when a discharge occurs between said electrodes, said element operating when heated to terminate the flow of electrical energy through said heater element.

6. A discharge device comprising an inner and an outer chamber, an ionizable medium and electrodes at opposite ends of said inner chamber a heater element in said outer chamber, an electrical circuit for said heater, a bi-metallic element in said circuit and positioned Within said outer chamber and intermediate said electrodes to be heated when a discharge occurs between said electrodes, said element operating when heated to terminate the flow of electrical energy through said heater element, and operable to cause a flow of electrical energy through said heater in the absence of heat upon a termination of said discharge.

7. A discharge device comprising a generally cylindrical inner envelope containing an ionizable medium and an electrode disposed therein adjacent each end, an enclosing generally cylindrical envelope, means for supporting said inner envelope in said enclosing envelope and including conductors electrically connected to said e1ectrodes, and a heater element in thespace between said envelopes, said heater element being con-.

'nected across said conductors in series with a bimetallic cut-out element traversing a substantial part of the length of said inner envelope, whereby when the device is operated current first passes through said heater and bimetallic elements until the temperature of the inner envelope is raised sufliciently to cause a discharge between said electrodes, with the eventual opening of the circuit through said heater element by the thermal actuation of said bimetallic element.

8. A discharge device comprising a sealed 'envelope containing an ionizable medium, electrodes, a heater element and circuit including said element, a heat-responsive device for making and breaking said circuit, a discharge circuit including said electrodes when said medium is ionized to carry a discharge current, said heat-responsive device being positioned between said electrodes and adjacent the path of said discharge current, and operating to break said heater circuit when said current elevates the temperature of said device to a predetermined degree, and causing current to again flow through said heater element upon a decrease in the temperature of said device to one below that breaking said circuit.

9, A discharge device comprising sealed outer and inner envelopes, an ionizable medium and a pair of electrodes in said inner envelope, a heater element in said outer envelope positioned to radiate heat energy to said inner envelope, means for causing a flow of electrical energy through said inner envelope and producing a discharge between EARL C. BRUECKMANN. 

